Angled turbulator for use in heat exchangers

ABSTRACT

A turbulator ( 60 A- 60 K) is provided for use in the heat exchange units ( 34 ) of heat exchangers. The turbulator ( 60 A- 60 K) includes a sheet ( 62 A,  62 C) of material. The sheet ( 62 A,  62 C) includes a plurality of strand-like rows ( 64 A,  64 C) of alternating crests ( 66 A,  66 C) and valleys ( 68 A,  68 C). The crests ( 66 A,  66 C) and valleys ( 68 A,  68 C) in each row ( 64 A,  64 C) are offset with respect to the crests ( 66 A,  66 C) and valleys ( 68 A,  68 C) in any immediately adjacent row ( 64 A,  64 C). Each of the rows ( 64 A,  64 C) has an interface with any immediately adjacent row ( 64 A,  64 C). The interfaces are perforated so that valleys ( 68 A,  68 C) in each row ( 64 A,  64 C) are in fluid communication with immediately adjacent crests ( 66 A,  66 C) in any immediately adjacent row ( 64 A,  64 C) and crests ( 66 A,  66 C) in each row ( 64 A,  64 C) are in fluid communication with any immediately adjacent valleys ( 68 A,  68 C) in any immediately adjacent row ( 64 A,  64 C). In some preferred embodiments ( 60 A,  60 C,  60 D,  60 E,  60 F,  60 H,  60 J,  60 K), the plurality of rows ( 64 A,  64 C) are divided into at least two groups ( 76 A,  76 C,  76 J;  78 A,  78 C,  78 J) which together define a herringbone pattern of the crests ( 66 A,  66 C) and valleys ( 68 A,  68 C).

FIELD OF THE INVENTION

[0001] This invention relates to heat exchangers, and more particularlyto heat exchangers of the type having a plurality of heat exchange unitsin stacked relation as used, for example, in oil coolers.

BACKGROUND OF THE INVENTION

[0002] It is known to provide the heat exchange units of heat exchangerswith internal turbulators to improve the heat transfer characteristicsof the heat exchanger. In general, the turbulators cause the fluidflowing through the heat exchange units to flow in a turbulent manner,thereby enhancing the heat transfer characteristics of the heatexchanger. Further, it is common for the turbulators to provideadditional heat conductive paths through periodic contact points withthe walls of the heat exchange units, thereby further increasing heattransfer within the heat exchanger.

[0003] U.S. Pat. Nos. 3,732,921 to Hillicki, et al.; 3,743,011 to Frost;3,734,135 to Mosier; 3,763,930 to Frost; 4,360,055 to Frost; 4,561,494to Frost; 4,967,835 to Lefeber; and 5,078,209 to Kerkman, et al.disclose heat exchangers having heat exchange units with turbulatorstherein. These heat exchangers have proven to be extremely successful,particularly in applications such as cooling the lubricating oil of aninternal combustion engine. The disclosed structures are relativelysimple in design, inexpensive to fabricate and readily serviceable whenrequired. Nonetheless, there is a continuing desire to provideadditional advantages in heat exchanger structures, including, forexample, improved heat transfer characteristics, improved pressure dropcharacteristics, decreased weight and size, etc.

SUMMARY OF THE INVENTION

[0004] It is the principal object of the invention to provide a new andimproved turbulator for use in the heat exchange unit of heatexchangers, and more specifically, to provide a turbulator thatincreases the heat transfer capabilities of the heat exchanger and/ordecreases the pressure drop through the heat exchanger, thereby allowingfor reduction in the size and weight of a heat exchanger employing theturbulator.

[0005] According to one facet of the invention, a lanced and offsetturbulator for use in a heat exchanger is provided. The turbulatorincludes a sheet of material. The sheet includes a plurality ofstrand-like rows of alternating crests and valleys. The crests andvalleys in each row are offset with respect to the crests and valleys inany immediately adjacent row. Each of the rows has an interface with anyimmediately adjacent row. The interfaces are perforated so that valleysin each row are in fluid communication with immediately adjacent crestsin any immediately adjacent row and crests in each row are in fluidcommunication with any immediately adjacent valleys in any immediatelyadjacent row. The plurality of rows are divided into at least two groupswhich together define a herringbone pattern of the crests and valleys.

[0006] According to one facet of the invention, all the rows areparallel to each other.

[0007] According to one facet of the invention, the rows in one group ofthe at least two groups are at an acute angle with the rows of anothergroup of the at least two groups of rows.

[0008] According to one facet of the invention, a lanced and offsetturbulator for use in a heat exchanger is provided. The turbulatorincludes a sheet of material. The sheet includes a plurality ofstrand-like rows of alternating crests and valleys. The crests andvalleys in each row are offset with respect to the crests and valleys inany immediately adjacent row. Each of the rows has an interface with anyimmediately adjacent row. The interfaces are perforated so that valleysin each row are in fluid communication with immediately adjacent crestsin any immediately adjacent row and crests in each row are in fluidcommunication with any immediately adjacent valleys in any immediatelyadjacent row. The valleys are arranged to define a first series ofparallel channels at an acute angle with the rows, and the crests arearranged to define a first series of parallel ridges at the acute anglewith the rows.

[0009] According to another facet of the invention, the valleys arearranged to define a second series of parallel channels, the crests arearranged to define a second series of parallel ridges, and the first andsecond series of channels and ridges together define a herringbonepattern of the channels and ridges and the crests and valleys.

[0010] In one embodiment, the invention is incorporated in a heatexchanger including a heat exchange unit. The heat exchange unitincludes a first surface spaced generally parallel to a second surfaceto define a flow chamber, a flow inlet spaced from a flow outlet, and agenerally planar lanced and offset turbulator in the flow chamber. Theturbulator includes a sheet of material. The sheet has the plurality ofstrand-like rows of alternating crests and valleys, with the crests andvalleys in each row being offset with respect to the crests and valleysin any immediately adjacent row. Each of the rows has an interface withany immediately adjacent row. The interfaces are perforated so thatvalleys in each row are in fluid communication with immediately adjacentcrests and any immediately adjacent row and crests in each row are influid communication with immediately adjacent valleys in any immediatelyadjacent row. The valleys are arranged to define a first series ofparallel channels at an acute angle to a line defined by the shortestdistance between the flow inlet and the flow outlet. The crests arearranged to define a first series of parallel ridges at the acute angleto the line defined by the shortest distance between the flow inlet andthe flow outlet.

[0011] According to one facet of the invention, the first series ofparallel channels and the first series of parallel ridges areperpendicular with the rows.

[0012] According to one facet of the invention, the first series ofparallel channels and the first series of parallel ridges arenon-perpendicular with the rows.

[0013] According to one facet of the invention, the rows are parallel tothe line defined by the shortest distance between the flow inlet and theflow outlet.

[0014] Other objects and advantages will become apparent from thefollowing specification taken in connection with the accompanyingdrawings.

IN THE DRAWINGS

[0015]FIG. 1 is a fragmentary, side elevation of an engine block havingmounted thereon a heat exchanger in the form of an oil cooler employingturbulators embodying the invention, with a filter of the customary typein position superimposed on the oil cooler;

[0016]FIG. 2 is an enlarged, fragmentary, sectional view of the heatexchanger shown in FIG. 1 with a portion of the oil filter shown indotted lines;

[0017]FIG. 3 is a plan view of a turbulator made according to oneembodiment of the present invention;

[0018]FIG. 4 is a plan view of a turbulator made according to a secondembodiment of the invention;

[0019]FIG. 5 is an enlarged perspective view of the area marked as 5-5in FIGS. 3 and 4;

[0020]FIG. 6 is a plan view of a turbulator made according to a thirdembodiment of the invention;

[0021]FIG. 7 is a plan view of a turbulator made according to a fourthembodiment of the invention with a portion broken away;

[0022]FIG. 8 is an enlarged, partial sectional view taken along thelines 8-8 in FIGS. 6 and 7;

[0023]FIG. 9 is a plan view of a turbulator made according to a fifthembodiment of the invention;

[0024]FIG. 10 is an enlarged, partial sectional view taken along theline 10-10 in FIG. 9;

[0025]FIG. 11 is a plan view of a turbulator made according to a sixthembodiment of the invention;

[0026]FIG. 12 is a plan view of a turbulator made according to a seventhembodiment of the invention; and

[0027]FIG. 13 is a plan view of a turbulator made according to an eighthembodiment of the invention;

[0028]FIG. 14 is a plan view of a turbulator made according to a ninthembodiment of the invention;

[0029]FIG. 15 is a plan view of a turbulator made according to a tenthembodiment of the invention; and

[0030]FIG. 16 is a plan view of a turbulator made according to aneleventh embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Several exemplary embodiments of turbulators made according tothe invention are described herein and are illustrated in the drawingsin connection with an oil cooler for cooling the lubricating oil of aninternal combustion engine. However, it should be understood that theinvention may find utility in other applications and that no limitationto use as an oil cooler is intended except insofar as expressly statedin the appended claims.

[0032] With reference to FIG. 1, the block of an internal combustionengine is fragmentarily shown at 10 and has received thereon an oilcooler 12 for the lubricating oil for the engine. An oil filter 14 issecured to the oil cooler 12 and the latter additionally has coolantinlet and outlet lines 16 and 18 extending to the cooling system of theengine. Lubricating oil is directed to the oil cooler 12 via a passage20 in the block 10 and returning lubricating oil is received by theengine via a passage 22.

[0033] Turning to FIG. 2, the passage 22 is defined by a sleeve 24fixedly attached to the engine block 10 and terminating in a threadedend 26 which in turn receives an internally threaded extender 28inserted through a central opening in the oil cooler 12. The extender 28includes an externally threaded end 30 to which the oil filter 14 isconnected in a conventional fashion. The oil cooler 12 includes ahousing 32 and a plurality of heat exchange units, each generallydesignated 34, stacked within the housing 32 and held in place by twospaced header plates 36, 38 of the housing 32.

[0034] Referring to the heat exchange units 34, each is identical to theother and includes a metal top plate 40 and a metal bottom plate 42.Each of the top plates 40 is spaced generally parallel to the bottomplates 42 to define a flow chamber 43 in each of the heat exchange units34. The heat exchange units 34 are generally circular and have an outerperipheral edge, shown generally at 44 that is defined by the outeredges of the plates 40, 42 which are clinched and/or brazed together.Additionally, each of the heat exchange units 34 includes a flow inlet50, a flow outlet 52 and an inner seal joint 54 that surrounds thethreaded extender 28. The flow inlets 50 are spaced on the oppositesides of the joints 54 from the flow outlets 52. Each of the heatexchange units 34 further includes a planar, disc-like turbulator,generally designated 60, several embodiments of which will be describedin greater detail hereinafter, disposed between the top and bottomplates 40, 42 within the flow chamber 43. Further description of thestructural details of the oil cooler depicted is not necessary tounderstand the present invention, as it will be appreciated that a) theinvention may be incorporated in any heat exchanger utilizing heatexchange units that define a flow path between an inlet and an outlet,and b) such structural details may be wholly conventional and are wellknown.

[0035] A turbulator 60A made according to one embodiment of theinvention is shown in FIG. 3. A turbulator 60B made according to anotherembodiment of the invention is shown in FIG. 4. FIG. 5 shows an enlargedperspective view of the area marked 5-5 in FIG. 3 and a rotated,enlarged perspective view of the area marked 5-5 in FIG. 4. Each of theturbulators 60A and 60B comprises a sheet of material 62A having good,thermal conductivity, such as a sheet of steel, copper, brass, oraluminum. The sheet 62A has a plurality of integral strand-like rows64A, as illustrated schematically by the dashed lines in FIGS. 3 and 4,and as best seen in FIG. 5. Also, as seen in FIG. 5, each of the rows64A is defined by alternating crests 66A and valleys 68A. The crests 66Aand the valleys 68A in each row 64A are connected by side walls 69A thatare nominally perpendicular to the length of the row 64A. The crests 66Aand the valleys 68A in each row 64A are offset in a staggered patternwith respect to the crests 66A and valleys 68A in any immediatelyadjacent row 64A. This offset creates windows or perforations 70A in theinterfaces between immediately adjacent rows 64A so that the valleys 68Ain each row are in fluid communication with immediately adjacent crests66A in any immediately adjacent row 64A and the crests 66A in each row64A are in fluid communication with any immediately adjacent valley 68Ain any immediately adjacent row 64A.

[0036] As shown schematically by the dashed lines in FIGS. 3-5, thevalleys 68A are arranged to define a series of parallel channels 72A andthe crests 66A are arranged to define a first series of parallel ridges74A. The parallel channels 72A and the parallel ridges 74A extend at anacute angle θ to a line X defined by the shortest distance between theflow inlet 50 (shown in phantom) and the flow outlet 52 (shown inphantom) of the heat exchange unit 34.

[0037] In one preferred embodiment as shown in FIG. 3, θ equals 30°. Inanother preferred embodiment as shown in FIG. 4, θ equals 60°.

[0038] Specifically with respect to the turbulator 60A shown in FIG. 3,the rows 64A are divided into two groups 76A and 78A which togetherdefine a herringbone pattern of the crests 66A and the valleys 68A andof the channels 72A and the ridges 74A. The herringbones have an acuteangle equal to 2θ. It should be noted that the rows 64A in group 76A arenot parallel to the rows 64A in the group 78A and are at an acute anglewith each other. It should also be noted that the channels 72A and theridges 74A in each of the two groups 76A, 78A are perpendicular to therows 64A in each of the two groups 76A, 78A, respectively.

[0039] Specifically with respect to the turbulator 60B shown in FIG. 4,the rows 64A are not divided into two groups, but rather form a singlegroup that defines the parallel channels 72A and the parallel ridges 74Athat are at the acute angle Θ to the line X defined by the shortestdistance between the flow inlet 50 and the flow outlet 52 of the heatexchange unit 34.

[0040] Turbulators 60C and 60D, made according to two additionalembodiments of the invention, are illustrated in FIGS. 6 and 7,respectively. Each of the turbulators 60C and 60D comprises a sheet ofmaterial 62C having a good thermal conductivity, such as steel, copper,brass, or aluminum. The sheet 62C includes a plurality of strand-likerows 64C, as illustrated schematically by the dashed lines in FIGS. 6and 7, and as shown in FIG. 8.

[0041] As best seen in FIG. 8, the rows 64C are defined by alternatingcrests 66C and valleys 68C. The crests 66C and the valleys 68C in eachrow 64C are connected by side walls 69C that are nominally perpendicularto the length of the row 64C. The crests 66C and the valleys 68C in eachrow 64C are offset with respect to the crests 66C and the valleys 68C inany intermediately adjacent row 64C. Unlike the back and forth staggeredoffset utilized in the turbulators 60A and 60B, the offset in theturbulators 60C and 60D is progressive, with each subsequent row 64Cbeing offset from the previous row 64C in the same direction. Thisoffset creates windows or perforations 70C in the interfaces betweenimmediately adjacent rows 64C so that the valleys 68C in each row 64Care in fluid communication with immediately adjacent crests 66C in anyimmediately adjacent row 64C and crests 66C in each row 64C are in fluidcommunication with any immediately adjacent valley 68C in anyimmediately adjacent row 64C.

[0042] As shown schematically by the dashed lines in FIGS. 6 and 7, thevalleys 68C are arranged to define a series of parallel channels 72Cthat are at an acute angle α with the rows 64C. The crests 66C arearranged to define a series of parallel ridges 74C that are also at theacute angle α with the row 64C.

[0043] In one preferred embodiment, α equals 30°. In another preferredembodiment, α equals 60°. In yet another preferred embodiment, α equals45°.

[0044] The rows 64C are divided into two groups 76C and 78C, whichtogether define a herringbone pattern of the crests 66C and valleys 68Cand of the channels 72C and ridges 74C. The two groups 76C and 78Cmaking up the herringbone have an angle equal to 2α between them.

[0045] A turbulator 60E, made according to yet another embodiment of theinvention, is illustrated in FIGS. 9 and 10. The structural details ofthe turbulator 60E are identical to the structural details of theturbulators 60C and 60D shown in FIGS. 6-8, with the exception that itsside walls 69C are at an acute angle ψ to the length of the rows 64C,rather than extending nominally perpendicular to the length of the rows64C. FIG. 11 shows yet another turbulator 60F that is structurallyidentical to the turbulator 60E, with the exception that its side walls69C extend at an obtuse angle ψ, rather than extending at an acute angleψ. Thus, the angle ψ of the side walls 69C in the turbulator 60E runs inthe direction of the angle α of the channels 72C and the ridges 74C,while the angle ψ of the side wall 69C in the turbulator 60F runsagainst the angle α of the channels 72C and the ridges 74C.

[0046] In one preferred embodiment ψ equals 45°. In another preferredembodiment ψ equals 30°. In yet another preferred embodiment ψ equals135°. In another preferred embodiment ψ equals 120°.

[0047] It should be noted that the rows 64C extend parallel to lines Xdefmed by the shortest distance between the flow inlet 50 and the flowoutlet 52 in FIG. 6 and between a flow inlet 80 and a flow outlet 82 inFIGS. 7, 9, and 11.

[0048] It should also be noted that, as seen in FIGS. 9 and 11, the sidewalls 69C of the center row 64C of the turbulators 60E and 60F arenominally perpendicular to the length of the rows 64C, rather than atthe angle ψ.

[0049] It should be understood that the relative position of the inlets50, 80 and outlets 80, 82 for the turbulator 60A, 60C, 60D, 60E, and 60Fcan be switched so that the flow from the inlets 50, 80 is directed intothe point of the herringbone pattern rather than into the bite of theherringbone pattern.

[0050] As shown in FIG. 12, a turbulator 60G can be made according tothe embodiments of 60C, 60D, 60E and 60F without dividing the rows 64Cinto two groups, that is, similar to the turbulator 60B shown in FIG. 4.

[0051] A turbulator 60H, made according to yet another embodiment of theinvention, is illustrated in FIG. 13. The structural details of theturbulator 60H are identical to the structural details of theturbulators 60C and 60D shown in FIGS. 6-8, with the exception that thegroups 76C and 78C of the rows 64C are repeated to define a repeatingherringbone pattern of the crest 66C and valley 68C and of the channels72C and ridges 74C.

[0052] A turbulator 60I, made according to yet another embodiment of theinvention, is illustrated in FIG. 14. The structural details of theturbulator 60I are a combination of selected structural details from theturbulators 60A and 60B shown in FIGS. 3-5 and the turbulators 60C, 60D,and 60G shown in FIGS. 6-8 and 12. More specifically, a plurality ofgroups 90I of rows 64A are provided in the turbulator 60I, with eachgroup 90I consisting of ten rows 64A that when viewed as a group arestructurally identical to the rows 64A described in connection with theturbulators 60A and 60B. Thus, for each group 90I, the crests 66A andthe valleys 68A have the same back and forth staggered offset as thatdescribed for the crests 66A and the valleys 68A of the turbulators 60Aand 60B. This produces a series of parallel channels 72A and parallelridges 74A within each group 90I that are nominally perpendicular to therows 64A. However, the groups 901 are offset from each other in aprogressive pattern, with each subsequent group 90I being offset fromthe previous group 90I in the same direction. More specifically,relative to each other, the groups 90I are staggered at their interfaces921 with adjacent groups 90I so that at each interface 921 there arefour rows 941 that when viewed as a group are structurally identical tothe rows 64C described in connection with the turbulators 60C, 60D and60G, with crests 66C and valleys 68C that are offset in a progressivepattern, rather than in the back and forth staggered pattern of theturbulators 60A and 60B. This produces a series of parallel channels 72Cand ridges 74C that are at an acute angle α with the rows 64A, 94I.

[0053] A turbulator 60J, made according to yet another embodiment of theinvention is illustrated in FIG. 15. The structural details of theturbulator 60J are identical to the structural details of the turbulator60I shown in FIG. 14, with the exceptions that a) the rows 64A, 94I, runtransverse to the major dimension of the turbulator 60J; b) groups 90Jare formed from four rows 64A, rather than ten rows 64A as for thegroups 90I; and c) the groups 90J are divided into two larger groups 76Jand 78J, which together define a herringbone pattern of the groups 90J.

[0054] A turbulator 60K, made according to yet another embodiment of theinvention is illustrated in FIG. 16. The structural details of theturbulator 60K are identical to the structural details of the turbulator60I shown in FIG. 14, with the exceptions that a) groups 90K are formedfrom five rows 64C rather than ten rows 64C and b) the groups 90K areoffset in a repeating back and forth staggered pattern to define arepeating herringbone pattern of the groups 90K, rather than in theprogressive offset pattern of the groups 90I in the turbulator 60I.

[0055] While flow inlets and outlets may be located at any convenientlocation, preferred locations for flow inlets 80H, 80V, and flow outlets82H, 82V are shown schematically by the dashed lines in FIGS. 13-16.When the flow inlet 80H and the flow outlet 82H are used together, theturbulators 60G, 60I, 60J, and 60K deliver relatively high heattransfers at relatively high pressure drops in comparison to the heattransfers and pressure drops provide when the flow inlet 80V and theflow outlet 82V are used together. Conversely, when the flow inlet 80Vand flow the flow outlet 82V are use together with the turbulator 60H,the turbulator 60H delivers relatively high heat transfers at arelatively high pressure drops in comparison to when the inlet 80H andthe outlet 82H are used together with the turbulator 60H.

[0056] It should be appreciated that the gross shape of the turbulators60A, 60B, 60C, 60D, 60E, 60F, 60G, 60H, 60I, 60J, and 60K is dictated bythe geometry of the heat exchange units 34 into which they areinstalled, and that the invention is not limited to the disclosed grossshapes.

[0057] Turning to Table A and FIGS. 8 and 10, one set of preferrednominal dimensions for the turbulators 60C, 60D, 60E, 60F, 60G, 60H,60I, 60J, and 60K are provided. It should be understood that thesedimensions may be used to define the turbulators 60A and 60B shown inFIGS. 3-5.

[0058] The dimension A is the amount of offset between one row 64C andan adjacent row 64C. As noted earlier, for the turbulators 60A and 60B,this offset is repeated back and forth from one row 64A to the next row64A to create a staggered pattern best seen in FIG. 5, while for theturbulators 60C, 60D, 60E, 60F, and 60G the offset is progressive, witheach subsequent row being offset in the same direction from the previousrow as seen in FIGS. 6-11.

[0059] The dimension B defines the crest to crest pitch for each of therows 64C. The dimension C defines a length for each of the crests 66Cand for each of the valleys 68C. The dimension T defines the thicknessof the sheet 62C. The dimension D defines the length of overlap betweenadjacent rows 64C. The dimension H defines the height of the turbulator60C, 60D, 60E, 60F, and 60G. The dimension W defines the width to beconsistent with length used to describe rows 64A at page 8, line 23, androws 64C at page 10, line 19, and page 11, line 24. R indicates theradius of each of the crests 66C and the valleys 68C. The angles E aredefined by the upward and downward slopes of each of the crests 66C andeach of the valleys 68C, and preferably are equal in magnitude. Theangle F is equal to 6° and defines the slope at the crown of each of thecrests 66C and each of the valleys 68C. TABLE A (Figures shown ininches) A B C D H T R W .071″ .281″ .108″ .033″ .083″ .010″ .035″ .058″

[0060] The turbulators 60A, 60B, 60C, 60D, 60E, 60F, 60G, 60H, 60I, 60J,and 60K may be manufactured using known techniques.

[0061] Test results comparing conventional turbulators with turbulatorsembodying the present invention have shown that the inventiveturbulators can provide increased heat transfer performance at a givenoil pressure drop, and a lower oil pressure drop at a given heattransfer rate. This increased performance will allow a heat exchangerhaving a fixed desired heat transfer capacity, such as an oil cooler, tobe made with fewer heat exchange units, thereby reducing its cost, size,and weight.

What is claimed is:
 1. A lanced and offset turbulator for use in a heatexchanger, the turbulator comprising: a sheet of a material, said sheetincluding a plurality of strand-like rows of alternating crests andvalleys, the crests and valleys in each row being offset with respect tothe crests and valleys in any immediately adjacent row, each of saidrows having an interface with any immediately adjacent row, saidinterfaces being perforated so that valleys in each row are in fluidcommunication with immediately adjacent crests in any immediatelyadjacent row and crests in said each row are in fluid communication withany immediately adjacent valleys in said any immediately adjacent row,said plurality of rows being divided into at least two groups whichtogether define a herringbone pattern of said crests and valleys.
 2. Theturbulator of claim 1 wherein all of the rows are parallel to eachother.
 3. The turbulator of claim 1 wherein the rows in one group ofsaid at least two groups are at an acute angle with the rows of anothergroup of said at least two groups.
 4. The turbulator of claim 1 whereinsaid herringbone pattern is characterized by herringbones having anapproximately a 60 degree included angle.
 5. The turbulator of claim 1wherein said herringbone pattern is characterized by herringbones havingapproximately a 120 degree included angle.
 6. A lanced and offsetturbulator for use in a heat exchanger, the turbulator comprising: asheet of a material, said sheet including a plurality of strand-likerows of alternating crests and valleys, the crests and valleys in eachrow being offset with respect to the crests and valleys in anyimmediately adjacent row, each of said rows having an interface with anyimmediately adjacent row, said interfaces being perforated so thatvalleys in each row are in fluid communication with immediately adjacentcrests in any immediately adjacent row and crests in said each row arein fluid communication with immediately adjacent valleys in said anyimmediately adjacent row, a first set of said valleys being arranged todefine a first series of parallel channels at an acute angle with saidrows, and a first set of said crests being arranged to define a firstseries of parallel ridges at said acute angle with said rows.
 7. Theturbulator of claim 6 wherein said acute angle is approximately 30degrees.
 8. The turbulator of claim 6 wherein said acute angle isapproximately 60 degrees.
 9. The turbulator of claim 6 wherein a secondset of said valleys are arranged to define a second series of parallelchannels at an acute angle with said rows, a second set of said crestsare arranged to define a second series of parallel ridges at an acuteangle with said rows, and said first and second series of channels andridges together define a herringbone pattern of the channels and ridges.10. The turbulator of claim 6 wherein a second set of said valleys arearranged to define a second series of parallel channels perpendicularwith said rows, and a second set of said crests are arranged to define asecond series of parallel ridges perpendicular with said rows, the firstand second sets of valleys having at least one valley in common, thefirst and second sets of crests having at least one crest in common. 11.In a heat exchanger including a heat exchange unit, said heat exchangeunit including a first surface spaced generally parallel to a secondsurface to define a flow chamber, a flow inlet spaced from a flowoutlet, and a generally planar, lanced and offset turbulator in the flowchamber, said turbulator including a sheet of a material, said sheethaving a plurality of strand-like rows of alternating crests andvalleys, the crests and valleys in each row being offset with respect tothe crests and valleys in any immediately adjacent row, each of saidrows having an interface with any immediately adjacent row, saidinterfaces being perforated so that valleys in each row are in fluidcommunication with immediately adjacent crests in any immediatelyadjacent row and crests in said each row are in fluid communication withany immediately adjacent valleys in said any immediately adjacent row;the improvement wherein: a first set of said valleys are arranged todefine a first series of parallel channels at an acute angle to a linedefined by the shortest distance between the flow inlet and the flowoutlet, and a first set of said crests are arranged to define a firstseries of parallel ridges at said acute angle to said line defined bythe shortest distance between the flow inlet and the flow outlet. 12.The improvement of claim 11 wherein: said first series of parallelchannels are perpendicular with said rows, and said first series ofparallel ridges are perpendicular with said rows.
 13. The improvement ofclaim 11 wherein: said first series of parallel channels arenon-perpendicular with said rows, and said first series of parallelridges are non-perpendicular with said rows.
 14. The improvement ofclaim 11 wherein said rows are parallel to said line defined by theshortest distance between the flow inlet and the flow outlet.
 15. Theimprovement of claim 11 wherein said first and second surfaces and saidturbulator are generally planar.
 16. The improvement of claim 11 whereinsaid acute angle is approximately 30 degrees.
 17. The improvement ofclaim 11 wherein said acute angle is approximately 60 degrees.
 18. Theimprovement of claim 11 wherein a second set of said valleys arearranged to define a second series of parallel channels, a second set ofsaid crests are arranged to define a second series of parallel ridges,and said first and second series of parallel channels and parallelridges together define a herringbone pattern of channels and ridges. 19.The improvement of claim 11 wherein a second set of said valleys arearranged to define a second series of parallel channels perpendicularwith said rows, and a second set of said crests are arranged to define asecond series of parallel ridges perpendicular with said rows, the firstand second sets of valleys having at least one valley in common, thefirst and second sets of crests having at least one crest in common.